The trial court’s order is significant in several respects, but in particular because it rejects plaintiff’s attempt to establish causation based on epidemiologic studies that do not show a relative risk of at least 2.0 for the specific cancer alleged by plaintiff.

The case was the first trial of clams by plaintiffs in coordinated proceedings alleging they developed ovarian cancer as a result of their use of Johnson’s Baby Powder and Shower to Shower. The case was brought by the daughter of Eva Echeverria, who died of serious invasive ovarian cancer. Plaintiff alleged that the talc in these products was the cause of Ms. Echeverria’s cancer. The case went to trial against Johnson & Johnson and its subsidiary Johnson & Johnson Consumer Inc. (JJCI) on a theory of negligent failure to warn.

The trial court granted judgment notwithstanding the verdict in favor of JJCI on the ground that plaintiff failed to show specific causation. The court granted judgment notwithstanding the verdict in favor of Johnson & Johnson on the ground that JJCI, rather than Johnson & Johnson, manufactured the products and plaintiff did not allege any theory (such as alter ego or agency) for holding the parent liable for the acts of the subsidiary. In the alternative, the court also granted defendants a new trial on several grounds including insufficiency of the evidence as to causation and excessive damages.

To establish specific causation, plaintiffs offered the expert opinion testimony of Ms. Echeverria’s treating physician, Dr. Annie Yessaian. Dr. Yessaian engaged in a “differential etiology” analysis (akin to a differential diagnosis) and opined that it was more probable than not defendants’ products caused Ms. Echeverria’s disease.

Dr. Yessaian relied on four epidemiologic studies that she testified showed a relative risk in excess of 2.0 that a woman using talc would develop ovarian cancer. Plaintiff presented expert opinion testimony that “relative risk” is the ratio of the risk among persons exposed as compared to those unexposed, so that if the risk of cancer “is 4 percent in the general population but among a group of people with a certain environmental exposure it is 6 percent, the relative risk of cancer due to that environmental exposure would be 6 percent divided by 4 percent equals 1.5.”

A relative risk of 2.0 is “the point at which the probability of causation, which is the probability that a given agent causes a specific disease, exceeds 50 percent.” [Ed. Note: For more information on relative risk, see a March 2017 WLF Working Paper.]

The trial court ruled that Dr. Yessaian’s testimony did not establish specific causation. First, the four studies that Dr. Yessaian identified as establishing a relative risk greater than 2.0 did not show such a relative risk for Ms. Echeverria’s specific cancer. Instead, Dr. Yessaian admitted that she knew of no studies showing a relative risk of 2.0 for Ms. Echeverria’s serious invasive ovarian cancer. Two of the studies did not break out serious invasive ovarian cancer. The two that did showed a relative risk of 1.70.

Dr. Yessaian also relied on other studies to show that talc was a scientifically plausible cause of serious ovarian cancer. But these other studies showed relative-risk ratios well below 2.0, at an average ratio of about 1.3. The trial court ruled that these results tended to disprove causation, as they showed that talc did not double the risk of harm. As the court explained, a risk ratio of 1.3 is well below the two-fold risk level necessary to show that talc “more probably than not” causes cancer.

The trial court ruled that Dr. Yessaian’s “differential etiology” did not make up for the shortcoming in her analysis. To employ such a differential analysis, Dr. Yessaian was first required to establish talc is a probable cause of ovarian cancer. Without establishing that threshold fact, she could not “rule in” talc as a probable cause of Ms. Echeverria’s disease. But Dr. Yessaian relied only on the epidemiologic studies to “rule in” talc, and her reliance on these studies failed for the reasons already discussed.

As an independent basis for its ruling, the trial court concluded that Dr. Yessaian failed to properly use her “differential etiology” because she did not properly rule out alternative causes of the disease. Instead, she conceded that idiopathic causes are the leading cause of ovarian cancer and that it was probable that Ms. Echeverria’s cancer was caused by unknown risk factors. Although Dr. Yessaian also testified inconsistently that there was less than a 50% chance Ms. Echeverria’s cancer was idiopathic, she offered no reasoning for the latter conclusion and the trial court rejected it as speculative.

The trial court’s order demonstrates the importance of a careful analysis of epidemiologic studies when offered to establish specific causation. As the trial court recognized, such studies must show a relative risk of at least 2.0 for plaintiff’s cancer, not just for cancer generally. If not, the studies fail to establish a basis for expert opinion testimony on the issue of causation.